GB2133116A - Pressure fluid supply valve - Google Patents

Abstract

Control means are provided for use in a pressure fluid line 11, 12, comprising a valve arrangeable in the pressure fluid line, the valve being such that if there is a reduction in pressure on the downstream side of the valve such as to indicate a burst or substantial leak, the valve acts to stop or restrict flow through the valve. When the valve is positioned in a high pressure line valve spindle 19 is raised so that a substantial quantity of fluid can flow past the sealing face 20. If however there is a sudden drop in pressure on the downstream side of the valve the spring 28 returns the valve spindle to the position shown and flow can only take place through the restriction element 30. <IMAGE>

Description

SPECIFICATION Pressure fluid supply systems The invention relates to pressure fluid supply systems, and in particular, but not exclusively, to such systems for use in the mining industry.

Pressure fluid supply for use at mine workings is commonly provided by a closed circuit or ring main system incorporating a tank and pump, whereby after utilisation of the fluid pressure, the fluid is exhausted and is subsequently returned to the tank by the pump for re-circulation. An alternative known system relies on the depth of mine workings, in which it is possible to draw fluid from a reservoir on the surface, and due to the head, utiiise the resultant pressure at the mine workings. The invention is equally applicable to both known types of fluid pressure supply system and the invention may also have other useful applications.

Severe problems can occur with either system if a pipe bursts or a substantial leak appears in the system, particularly on the pressure side.

The invention provides control means for use in a pressure fluid line, comprising a valve arrangeable in the pressure fluid line, the valve being such that if there is a reduction in pressure on the downstream side of the valve such as to indicate a burst or substantial leak, the valve acts to stop or restrict flow through the valve.

The invention is not suitable for use with underground fire-fighting mains since when a first-fighting main is in use, there may be a substantial reduction in pressure in the main but maximum flow is still required.

Preferably the valve is such that if the reduced pressure rises again to a predetermined level, indicating repair of the burst or stoppage of the leak, the valve acts to restore full flow.

The valve may comprise a valve body having an inlet port for connection to the upstream pressure fluid line, an outlet port for connection to the downstream pressure fluid line, a closure member, and a restriction member acting between the said ports, wherein engagement of the closure members causes flow to take place through the said restriction member, thus limiting the flow of fluid passing from the inlet port to the outlet port.

The valve may be such that the closure member moves towards its engaged position after sensing a sudden reduction in pressure at the outlet port and moves away from its engaged position after sensing a predetermined fluid pressure in the outlet port.

There may be a valve spindle acting in a valve chamber between the inlet port and the outlet port.

Preferably the valve chamber is in communication with the inlet port, the restriction member is positioned in a wall between the valve chamber and the outlet port and there is a passage between the valve chamber and the outlet port, bypassing the restriction member, which can be opened and closed by a first head of the valve spindle.

The valve spindle may have a second head acting in a control chamber, the control chamber being in communication with the outlet port so that when pressure in the outlet port reaches the desired level pressure in the control chamber rises to move the valve away from its engaged position.

The control chamber may be in communication with the outlet port via a passage which extends through the valve spindle.

It may be possible to close the restriction member to stop flow completely.

By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a vertical cross-section through a first embodiment of valve according to the invention; and Figure 2 is a horizontal cross-section through the valve body of an alternative embodiment of valve according to the invention.

The valve comprises a body 10 having an inlet port 11 and an outlet port 12. The inlet port 11 is in direct communication with a valve chamber 1 5 and additional ports 1 3 and 14 extend between the valve chamber 1 5 and the outlet port 12.

Port 13 is sealed by a plug 16 and port 14 is sealed by a plug 17.

At the lower end of the valve chamber 1 5 is a valve seating member 18 which guides a valve spindle 1 9 by engagement with the lower part of the valve spindle 1 9. The valve seating member 1 8 also provides a sealing surface which, when the valve spindle is in the position shown in the Figure, seals against the conical sealing face 20 of the valve spindle, thus preventing communication between the port 13 and the valve chamber 1 5.

In addition to its lower head, the valve spindle 19 has an upper head in the form of a piston 24 which slides in a control chamber in the form of a combined guide and housing 21. The housing 21 seals against the valve body at 22 and against the valve spindle at 23 so that fluid cannot pass directly from the valve chamber 1 5 into the housing 21. There is a seal 25 between the piston 24 and the inner face of the housing 21.

At the upper end of the housing 21 there is a plug 26 into which is threaded an adjusting screw 27. A compression spring 28 is interposed between the plug 26 and the valve spindle 19, biasing the valve spindle downwardly.

The control chamber is in communication with the port 13 via a fluid passage 29 which extends through the valve spindle from the port 1 3 to the underside of the piston 24.

A restriction element 30 is inserted in a wall of the valve between the port 14 and the valve chamber 1 5.

For convenience the valve spindle 19 is made in two parts and held together by a nut 31.

The adjusting screw 27 has an extended spigot 32, which, if the adjusting screw is screwed downwardly, engages the spindle 1 9. The housing 21, above the piston 24, has a vent 33 to atmosphere. A regulating orifice 34 is provided at the lower end of the passage 29.

In operation the valve is placed in a pressure fluid supply line at a convenient place away from points where the line is vulnerable to external movements and resultant damage. At commencement of the valve operation, i.e. after start-up of a supply pump or connection to other fluid pressure supply, fluid under pressure enters the valve through the port 11 and passes into the chamber 1 5. At this stage the valve spindle is in the engaged position shown in Figure 1 and fluid may only pass to the outlet port 12 through the restrictor 30, for onward flow to the services utilising the fluid pressure, for example the hydraulic jacks of mine roof supports.

After adequate fluid under pressure has passed through the restrictor 30, a pressure build-up will occur allowing a similar pressure to be achieved in the housing 21 on the underside of the piston 24, via the orifice 34 and passageway 29. This pressure overcomes the force of the spring 28 and lifts the spindle 29, allowing fluid under pressure to pass from the chamber 15, between the sealing face 20 and seating member 18, and thence to the outlet port 12 via ports 13 and 14. The guided part of the spindle 1 9 passing through the seating member 1 8 has a series of flats or grooves thereon to allow fluid to pass between the guided portion of the spindle and the seating member 18 once the conical sealing face 20 of the valve spindle has moved away from the seating member 18.

Thus during normal operation flow can take place over a relatively large area, thus reducing localised fluid velocity and hence erosion damage.

Should there be a sudden reduction in pressure at the outlet port however, for example resulting from a burst pipe, there is a corresponding drop in pressure in the valve control chamber underneath the piston 24 and the spring 28 is able to return the valve member to its engaged position shown in Figure 1. There is thus no substantial loss of fluid. Flow can only take place through the restrictor 30 and so fluid loss is controlled by the restrictor 30 until such time as an operative can close an adjacent valve (not shown) to terminate the fluid supply until the system is operational again.

Once the system is operational again, and the valve is in normal use again, there will be a buildup of pressure in the outlet port 12 which will cause the valve 19 to be moved away from its engaged position.

Until the system is operational again, it may be desirable to screw the adjusting screw 27 down to positively hold the spindle 1 9 in the position shown in Figure 1. If the spindle 1 9 is left under the control of the spring 28, the valve may tend to 'hunt', causing unnecessary vibration in the supply system, particularly in the case of a major leak.

Turning now to Figure 2, there is shown a valve which is generally simiiar to that shown in Figure 1, having a body 10, an inlet port 11, and an outlet port 12. The inlet port 11 is in direct communication with the valve chamber 1 5. The valve has a valve spindle which operates in the same way as valve spindle 1 9 of Figure 1, and can provide full flow from the valve chamber 1 5 to the outlet port 12.

The difference of this embodiment lies in the form of the restriction element. Instead of having a fixed restriction element between the valve chamber 1 5 and the outlet port 12, the element comprises a peg 35 having a tapered end 36. A passage 37 is drilled through the valve body into the outlet port 12 and its outer end 38 is plugged.

A port 39 is drilled between the passage 37 and the valve chamber 1 5.

The peg 35 projects from a threaded control member 40 which is screwed into the valve body, there being an O-ring 41 to provide a seal. By turning the knurled knob 42 of the control member the peg 35 can be moved towards and away from the port 39, to control the amount of fluid that can flow from the valve chamber 1 5 to the outlet port 12.

It is thus possible to shut off flow through the restriction member completely by screwing the control member 40 in until the tapered end 36 of the peg 35 closes the port 39.

With this embodiment it may be necessary to provide an adjacent valve since the restriction member can be used to provide complete shutdown until a burst or leak has been repaired.

The invention is not restricted to the details of the foregoing embodiments.

Claims (9)

1. Control means for use in a pressure fluid line, comprising a valve arrangeable in the pressure fluid line, the valve being such that if there is a reduction in pressure on the downstream side of the valve such as to indicate a burst or substantial leak, the valve acts to stop or restrict flow through the valve.

2. Control means as claimed in claim 1, in which the valve is such that if the reduced pressure rises again to a predetermined level, indicating repair of the burst or stoppage of the leak, the valve acts to restore full flow.

3. Control means as claimed in claim 2, in which the valve comprises a valve body having an inlet port for connection to the upstream pressure fluid line, an outlet port for connection to the downstream pressure fluid lines, a closure member, and a restriction member acting between the said ports, wherein engagement of the closure member causes flow to take place through the said restriction member, thus limiting the flow of fluid passing from the inlet port to the outlet port.

4. Control means as claimed in claim 3, in which the valve is such that the closure member moves towards its engaged position after sensing a sudden reduction in pressure at the outlet port and moves away from its engaged position after sensing a predetermined fluid pressure in the outlet port.

5. Control means as claimed in claim 4, in which there is a valve spindle acting in a valve chamber between the inlet port and the outlet port.

6. Control means as claimed in claim 5, in which the valve chamber is in communication with the inlet port, the restriction member is positioned in a wall between the valve chamber and the outlet port and there is a passage between the valve chamber and the outlet port, bypassing the restriction member, which can be opened and closed by a first head of the valve spindle.

7. Control means as claimed in claim 6, in which the valve spindle has a second head acting in a control chamber, the control chamber being in communication with the outlet port so that when pressure in the outlet port reaches the desired level pressure in the control chamber rises to move the valve away from its engaged position.

8. Control means as claimed in any one of claims 5 to 7 in which the control chamber is in communication with the outlet port via a passage which extends through the valve spindle.

9. Control means constructed and arranged substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.